[Amps] fiberglas tape : summary

[Will Matney]

George,

All I know is they used this in a certain amp that used a quantity of 12 M-2057 (modified 8908) tubes with an output of about 2000 watts PEP. The meter was mounted within 4-5 inches of the output tank coil and was not shielded. The meters I seen melt, but never the tape. The meter body looked to be made from styrene plastic like plastic models are. It would be the same white plastic they use now mostly on cheaper meters. This being the kind you can illuminate with a lamp behind it. I couldn't say what the fibers were in the tape, but they looked like maybe a glass type fiber, I'm not sure. The tape itself didn't melt, neither did the fibers. I know the manufacturer just used tape that they got the best deals on, so it could have been any composition. The tape they used was about 1-1/2" wide, not the 3/4" stuff but they both should be the same. I tried this with some 3M packing tape with the fibers, and it worked on some I home brewed. I think a lot is how close the meter is to the tank circuit. On a tank coil using a toroid, I'm not sure but it may or may not work. I have used it on smaller toroids handling 100 watts in input matching circuits and it held up ok. On them though, the thinner the tape the better as you fill up the hole and don't have space for the wire if you get it too thick. The large toroids like used in the output tank wouldn't be bad as the hole is a larger diameter. Ferrite toroids though supposed to be electrically non-conductive and act like a ceramic. Iron powder though is totally different. I've seen plenty of coils and RF transformers wrapped on ferrite cores without any tape at all, and they lasted for the life of the amp. Iron though uses an iron powder which is pressed under great pressure and heat to make a toroid similar to the way they make powdered metal gears in automobiles. It is conductive.

Best,

Will




*********** REPLY SEPARATOR  ***********

On 6/15/06 at 10:03 AM gdaught6 at stanford.edu wrote:

>Thanks to all who responded to my query about fiberglas tape.  
>
>The consensus was that Scotch 27 is the thing to use.
>
>Other suggestions were for strapping tape (like for packages) which 
>might work OK, but I don't know.  Some of them have glass fibers but 
>some have nylon or polyester fibers.
>
>Scotch 33 and 88 were also mentioned, but they are definitely NOT 
>fiberglas tapes.  They are high-quality black vinyl electrical tape.
>
>tnx agn es 73,
>
>George T. Daughters, K6GT
>
>
>
>
>_______________________________________________
>Amps mailing list
>Amps at contesting.com
>http://lists.contesting.com/mailman/listinfo/amps